The research, by Harmit Malik, Ph.D., and colleagues in Fred Hutchinson's Basic Sciences Division, is available on the Public Library of Science Web site and will appear in the journal's September print edition.
The work hinges on a recently discovered protein called Apobec3G, which has been generating some buzz in the scientific community for its potential in shedding light on the genetic mechanisms of HIV prevention. The protein defends cells from HIV infection by causing mutations in the genetic material within the virus. In response, HIV produces a protein that binds to Apobec3G and targets it for destruction.
Such conflicts, often dubbed "genetic arms races," typically put pressure on both sparring partners to continually evolve new ways to outsmart and overcome each other just to stay in the game. Such genetic tugs of war also exemplify what is known among evolutionary biologists as the Red Queen Principle, a phrase borrowed from the Red Queen in Louis Carroll's "Through the Looking Glass" that refers to the paradox of running as fast as you can just to stay in place.
When comparing human Apobec3G genes with those of man's distantly related primate relatives, Malik and colleagues found, to their surprise, that the protein began to evolve in response to such Darwinistic pressure more than 30 million years before HIV-like viruses first infected primates, an event that occurred about a million years ago.
"This suggests that HIV is a newcomer to this conflict," Malik said, "because the host can't evolve a completely new defense in such a short period of time."
The discovery of Apobec3G's continual evolution the result of the first detailed glimpse into the workings of a genome-defense system in which bot
Contact: Kristen Lidke Woodward
Fred Hutchinson Cancer Research Center